1. Field of the Invention
This invention relates to an electric circuit breaker and, more particularly, it pertains to an undervoltage trip mechanism in response to a voltage drop below a predetermined value on a power line.
2. Description of the Prior Art
Medium voltage switchgear has usually employed operating mechanisms that have a trip mechanism for separating a pair of electrical contacts. Such mechanisms have provided protection for an electrical circuit or system against electrical faults, such as overload conditions, load level short circuit, or fault current conditions, as well as high level short circuit conditions. In addition, prior art circuit breakers have utilized mechanisms for detecting undervoltage conditions and, for tripping circuit breakers upon the occurrence of undervoltage conditions, such as disclosed in U.S. Pat. Nos. 3,533,024 and 4,620,171.
Most undervoltage trip devices have offered high technology contrivances by virtue of the complexities of design as well as by various delicate assembly procedures. This invariably means that the cost of the device is high while functional reliability, if not low, is dependent upon frequent routine maintenance.